JPH11228112A - Ozone generator - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To alleviate the concentration of an electric field contributing to the ozone generation reaction, reduce the temperature rise due to discharge, and suppress the secondary decomposition of ozone and the generation of nitrogen oxides that increase with the temperature rise. ,
Provided is an ozone generation element having improved ozone generation efficiency. SOLUTION: In an ozone generating element provided with a discharge electrode 2 and a ground electrode 3 with a dielectric 1 interposed therebetween and a protective film 4 provided on the discharge electrode 2, the protective film 4 comes into contact with the discharge electrode 2. A first coating 41 and a second coating 42 superimposed on the first coating are provided. The dielectric constant of the second coating is larger than the dielectric constant of the first coating, and the angle of refraction of the lines of electric force is increased. The layer of the protective coating 4 can be sequentially increased by increasing the dielectric constant,

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ozone generating element for generating ozone by creeping discharge.

[0002]

2. Description of the Related Art Conventionally, a creepage discharge type ozone generator conventionally used for deodorization, sterilization, and the like, as shown in FIG. For example, a stainless steel plate having a thickness of 3 mm (SUS31
6) a discharge electrode 2 having a strip shape, and a ground electrode 3 having a stainless steel plate having a thickness of 3 mm wider than the discharge electrode 2 are provided.
An ozone generating element provided with a protective film 4 on the discharge electrode 2 is attached via an insulating plate 5, and a high-frequency high voltage is applied between the discharge electrode 2 and the ground electrode 3 to form a space above the discharge electrode 2. A surface discharge 6 is generated along the surface direction of the dielectric by breaking electric insulation, and a part of oxygen molecules contained in the source gas 7 passing through the electric field region in the chamber 10 is converted into ozone by the discharge energy. It is being converted.

[0004]

However, in such an ozone generating element, as shown in FIG. 5, electric lines of force generated from the discharge electrode 2 enter the protective film 4 from the discharge electrode 2 at an angle of θ ₁ . The electric field concentrates on a part of the source gas 7 in the vicinity of the discharge electrode 2 to generate the creeping discharge 6. For this reason, the temperature of this concentrated space portion rapidly rises due to the discharge, and not only is the ozone generated by the discharge decomposed by heat, but also when air is used as a raw material gas, the ozone is decomposed due to the temperature rise. There is a disadvantage in that the generation of promoted nitrogen oxides increases and the efficiency of the ozone generator decreases. Further, since the electric field region contributing to the ozone generation reaction is limited to the space in the vicinity of the discharge electrode, the discharge range is also limited to a narrow range, the contact range with the raw material gas is reduced, and the ozone generation of the creeping discharge type ozone generation element is reduced. Efficiency is low. An object of the present invention is to provide an ozone generation element that efficiently generates ozone by relaxing concentration of an electric field that contributes to an ozone generation reaction and expanding a discharge region.

[0005]

Accordingly, the present invention provides a surface discharge type ozone generator having a dielectric between a discharge electrode and a ground electrode, wherein a protective film provided on the discharge electrode has a dielectric constant. It is formed of two or more different coatings, and the dielectric constant of each coating is determined from the first coating closest to the discharge electrode.
The size is gradually increased toward the outer layer closest to the source gas.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One surface of a dielectric made of ceramic, mica, glass, or the like is provided with a discharge electrode for applying a high-frequency high voltage, and the other surface is provided with a ground electrode grounded. A first coating formed by a ceramic coating to have a uniform thickness is provided thereon, and a second coating having a dielectric constant larger than the first coating is provided on the first coating in a uniform thickness. Further, a plurality of layers of films having gradually increased dielectric constants may be provided on the first film. In addition, the thickness of the coating of each layer is 5 to 15 μm.
It is desirable that the thickness of the entire coating be 10 to 30 μm.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; In the drawings, the thickness of the coating is exaggerated for the sake of explanation. In FIG. 1, reference numeral 1 denotes a dielectric made of a material having good electrical insulation, heat resistance, and heat conductivity, for example, alumina ceramic, and has a discharge electrode 2 on one surface and a ground electrode 3 wider than the discharge electrode on the other surface. Is provided by a printing technique using a conductive paste. 4 is a discharge electrode 2
And a first coating 41 and a second coating 42. The first coating 41 has a relative dielectric constant of 1 on the discharge electrode 2.
A ceramic coating agent containing about 0 as a main component of alumina is applied to a uniform thickness of 8 μm by spin coating, spraying, dipping, roll coating or the like. Second
The coating 42 is provided on the first coating and has a higher dielectric constant than the first coating 41. In consideration of corrosion resistance due to electric discharge, a ceramic coating agent having a relative dielectric constant of 100 or more as a main component is titanium oxide. To form a uniform coating with a thickness of 10 μm. Note that the thickness of each of the coatings 41 and 42 may be the same or different.
The second coating may be formed uniformly at a thickness of about 15 μm, and the second coating may be subjected to high-temperature baking, which may cause thermal distortion in each part. Therefore, use an inorganic coating agent that is cured at room temperature, or temporarily bake the first coating. It is preferable to perform high-temperature baking together with the two coatings.

When a high-frequency high voltage is applied between the discharge electrode 2 and the ground electrode 3 from a power supply (not shown), creeping discharge is started in the raw material gas on the upper surface of the second coating, and ozone is generated. At this time, if the angle of electric lines of force generated from the discharge electrode 2 enters the first film having the dielectric constant E ₁ from the discharge electrode 2 as θ ₁ , the electric force lines when entering the interface of the second film having the different dielectric constant E ₂ refraction angle theta _{2 is, tanθ 1 / tanθ 2 = E} 1 / E because it is the _second relationship, E ₁ <E if ₂ theta ₁ <theta ₂
As shown in FIG. 2, the refractive index of the electric flux lines increases by entering the second coating having a large dielectric constant, and is compared with FIG. 5 showing the conventional electric flux lines without the second coating. As is apparent, the electric field due to the discharge spreads in the source gas 7 and the concentration is reduced. For this reason, it is possible to eliminate the occurrence of local discharge and reduce the rise in the space temperature, thereby suppressing the secondary decomposition of ozone due to heat and the generation of nitrogen oxides that increase with the rise in temperature. Further, the probability of contact between the source gas and the electric field is increased due to the expansion of the discharge space in the source gas, and the ozone generation efficiency is improved.

FIG. 3 shows a second embodiment, in which the same parts as those in FIG. 1 are denoted by the same reference numerals, and the first coating 41 is coated with an inorganic adhesive to form a prepreg state. The second coating 42 is formed by stacking high-ceramic sheets, and a third coating 43 is formed on the second coating with an inorganic coating agent having a dielectric constant higher than that of the second coating, and is cured by heating. The thickness is 5 to 15 μm, and the entire thickness of the protective coating 4 is smaller than that of the dielectric 1 and is about 30 μm. In this embodiment, the refraction of the lines of electric force can be further increased as compared with the first embodiment, and the electric field region in the source gas is widened to suppress local concentration. Although the number of coating layers can be further increased, the number of layers is preferably about three or four in order to maintain the electric field strength in consideration of the number of steps in the production.

[0011]

As described above, the present invention provides an ozone generating element having a discharge electrode and a ground electrode with a dielectric interposed therebetween, and a protective film provided on the discharge electrode.
The film is formed of multiple layers with different dielectric constants, and the dielectric constant of each layer coating is gradually increased from the one near the discharge electrode, so the angle of refraction when the lines of electric force enter the films with different dielectric constants increases. In addition, the electric field region in the source gas layer is widened and the concentration is relaxed, the temperature rise due to discharge is small, the secondary decomposition of ozone and the generation of nitrogen oxide which increases with the temperature rise are suppressed, and the contact between the source gas and the electric field is suppressed. Good
The effect of improving the ozone generation efficiency is obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing electric lines of force of the embodiment shown in FIG.

FIG. 3 is a side sectional view showing a second embodiment.

FIG. 4 is a side sectional view showing a conventional example attached to an ozone generator.

FIG. 5 is a characteristic diagram of electric lines of force in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric 2 Discharge electrode 3 Ground electrode 4 Protective film 41 First film 42 Second film 43 Third film 5 Insulating plate 6 Surface discharge 7 Source gas 10 Chamber

Claims (2)

[Claims] A discharge electrode and a ground electrode sandwiching a dielectric, a protective coating on the discharge electrode, and applying a high-frequency high voltage between the electrodes to generate a creeping discharge; The protective coating is formed of two or more coatings having different dielectric constants, and the dielectric constant of each coating is sequentially increased from the coating in contact with the discharge electrode toward the coating in contact with the source gas layer. Ozone generator. 2. The thickness of each layer of the protective coating is 5 to 10 μm.
The ozone generating element according to claim 1 or 2, wherein m is an overall thickness of 10 to 30 µm.